We’re all used to hearing of über-rich gazillionaires donating to charitable causes like finding cures for diseases and feeding hungry children in Africa. But what about websites? Now you can say that you’ve heard that too, as Google co-founder Sergey Brin has forked over $500,000 to Wikipedia.

The donation is actually from Brin’s charity, the Brin Wojcicki Foundation, which he founded with his wife, Anne Wojcicki. Before these big bucks were sent to the Wikimedia Foundation (the nonprofit that runs Wikipedia), the couple had donated to Michael J. Fox’s fund for finding a cure for Parkinson’s disease.

Perhaps Brin was touched by all of those “personal appeals” from Wikipedia founder Jimmy Wales. The pledge drive, prominently featured at the top of all Wikipedia articles for some time now, starts by stating that Google might have close to a million servers — compared to the mere 679 for Wikipedia. Maybe Brin looked at the nonprofit’s conundrum and decided he wanted to lend a hand from Mountain View.

In a way, Google and Wikipedia are like yin and yang. Google’s search engine lets people all over the world find information, while Wikipedia has become an easy, one-stop destination for much of that information. Search Google for a subject, and its Wiki entry is sure to be one of the first results. Likewise, if a Wiki reader wants to know about asparagus, he probably won’t go to wikipedia, search for the topic, and sort through the results — rather he’ll just search Google for “wiki asparagus” and click on the first result.

While it’s possible that Brin’s donation came from some Zen-like awareness of the interconnectedness of the two companies, but he most likely just thinks Wikipedia is a cool, useful service. We have all mined the (sometimes) reliable treasure trove of compiled information on the site, and many of us would have no problem sending them a few bucks. It just so happens that if you’re worth $17 billion, “a few bucks” comes out to half a million dollars.